diff --git a/.gitignore b/.gitignore
index 694f36e04..859459068 100644
--- a/.gitignore
+++ b/.gitignore
@@ -143,3 +143,4 @@ poetry.toml
 # Local scripts
 /run-vim.sh
 /run-chat.sh
+include/llguidance.h
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e7f520582..9cff219e1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -79,6 +79,7 @@ option(LLAMA_BUILD_SERVER   "llama: build server example" ${LLAMA_STANDALONE})
 
 # 3rd party libs
 option(LLAMA_CURL "llama: use libcurl to download model from an URL" OFF)
+option(LLAMA_LLGUIDANCE "llama: build LLGuidance library for structured output" OFF)
 
 # Required for relocatable CMake package
 include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/build-info.cmake)
diff --git a/common/json-schema-to-grammar.cpp b/common/json-schema-to-grammar.cpp
index 4d426b6bd..4b1401ef1 100644
--- a/common/json-schema-to-grammar.cpp
+++ b/common/json-schema-to-grammar.cpp
@@ -991,11 +991,15 @@ public:
 };
 
 std::string json_schema_to_grammar(const json & schema) {
+#ifdef LLAMA_LLGUIDANCE
+    return "llg:json:" + schema.dump();
+#else
     return build_grammar([&](const llama_grammar_builder & callbacks) {
         auto copy = schema;
         callbacks.resolve_refs(copy);
         callbacks.add_schema("", copy);
     });
+#endif
 }
 
 std::string build_grammar(const std::function<void(const llama_grammar_builder &)> & cb) {
diff --git a/common/llguidance.cpp b/common/llguidance.cpp
new file mode 100644
index 000000000..4120e93b2
--- /dev/null
+++ b/common/llguidance.cpp
@@ -0,0 +1,253 @@
+#ifdef LLAMA_LLGUIDANCE
+#include "llguidance.h"
+
+struct llama_sampler_llg {
+    const struct llama_model * model;
+    std::string grammar_kind;
+    std::string grammar_data;
+    LlgTokenizer *tokenizer;
+    LlgConstraint *grammar;
+    LlgMaskResult llg_res;
+    bool has_llg_res;
+};
+
+static LlgConstraint *llama_sampler_llg_new(LlgTokenizer *tokenizer,
+        const char * grammar_kind, const char * grammar_data) {
+    LlgConstraintInit cinit;
+    llg_constraint_init_set_defaults(&cinit, tokenizer);
+    auto c = llg_new_constraint_any(&cinit, grammar_kind, grammar_data);
+    if (llg_get_error(c)) {
+        LLAMA_LOG_ERROR("llg error: %s\n", llg_get_error(c));
+        llg_free_constraint(c);
+        return nullptr;
+    }
+    return c;
+}
+
+static const char * llama_sampler_llg_name(const struct llama_sampler * /*smpl*/) {
+    return "llguidance";
+}
+
+static void llama_sampler_llg_accept_impl(struct llama_sampler * smpl, llama_token token) {
+    auto * ctx = (llama_sampler_llg *) smpl->ctx;
+    if (ctx->grammar) {
+        LlgCommitResult res;
+        llg_commit_token(ctx->grammar, token, &res);
+        ctx->has_llg_res = false;
+    }
+}
+
+static void llama_sampler_llg_apply(struct llama_sampler * smpl, llama_token_data_array * cur_p) {
+    auto * ctx = (llama_sampler_llg *) smpl->ctx;
+    if (ctx->grammar) {
+        if (!ctx->has_llg_res) {
+            if (llg_compute_mask(ctx->grammar, &ctx->llg_res) == 0) {
+                ctx->has_llg_res = true;
+            } else {
+                LLAMA_LOG_ERROR("llg error: %s\n", llg_get_error(ctx->grammar));
+                llg_free_constraint(ctx->grammar);
+                ctx->grammar = nullptr;
+            }
+        }
+        if (ctx->has_llg_res) {
+            if (ctx->llg_res.is_stop) {
+                for (size_t i = 0; i < cur_p->size; ++i) {
+                    if (!llama_token_is_eog(ctx->model, cur_p->data[i].id)) {
+                        cur_p->data[i].logit = -INFINITY;
+                    }
+                }
+            } else {
+                const uint32_t *mask = ctx->llg_res.sample_mask;
+                for (size_t i = 0; i < cur_p->size; ++i) {
+                    auto token = cur_p->data[i].id;
+                    if ((mask[token / 32] & (1 << (token % 32))) == 0) {
+                        cur_p->data[i].logit = -INFINITY;
+                    }
+                }
+            }
+        }
+    }
+}
+
+static void llama_sampler_llg_reset(struct llama_sampler * smpl) {
+    auto * ctx = (llama_sampler_llg *) smpl->ctx;
+    if (!ctx->grammar) {
+        return;
+    }
+
+    auto * grammar_new = llama_sampler_llg_new(ctx->tokenizer, ctx->grammar_kind.c_str(), ctx->grammar_data.c_str());
+    llg_free_constraint(ctx->grammar);
+    ctx->grammar = grammar_new;
+    ctx->has_llg_res = false;
+}
+
+static struct llama_sampler * llama_sampler_llg_clone(const struct llama_sampler * smpl) {
+    const auto * ctx = (const llama_sampler_llg *) smpl->ctx;
+
+    auto * result = llama_sampler_init_llg(ctx->model, nullptr, nullptr);
+
+    // copy the state
+    {
+        auto * result_ctx = (llama_sampler_llg *) result->ctx;
+
+        if (ctx->grammar) {
+            result_ctx->grammar_kind = ctx->grammar_kind;
+            result_ctx->grammar_data = ctx->grammar_data;
+            result_ctx->grammar = llg_clone_constraint(ctx->grammar);
+            result_ctx->tokenizer = llg_clone_tokenizer(ctx->tokenizer);
+        }
+    }
+
+    return result;
+}
+
+static void llama_sampler_llg_free(struct llama_sampler * smpl) {
+    const auto * ctx = (llama_sampler_llg *) smpl->ctx;
+
+    if (ctx->grammar) {
+        llg_free_constraint(ctx->grammar);
+        llg_free_tokenizer(ctx->tokenizer);
+    }
+
+    delete ctx;
+}
+
+static struct llama_sampler_i llama_sampler_llg_i = {
+    /* .name   = */ llama_sampler_llg_name,
+    /* .accept = */ llama_sampler_llg_accept_impl,
+    /* .apply  = */ llama_sampler_llg_apply,
+    /* .reset  = */ llama_sampler_llg_reset,
+    /* .clone  = */ llama_sampler_llg_clone,
+    /* .free   = */ llama_sampler_llg_free,
+};
+
+
+static size_t llama_sampler_llg_tokenize_fn(const void *user_data,
+                                const uint8_t *bytes,
+                                size_t bytes_len,
+                                uint32_t *output_tokens,
+                                size_t output_tokens_len)
+{
+    const struct llama_model *model = (const struct llama_model *)user_data;
+    int r = llama_tokenize(model, (const char *) bytes, bytes_len, 
+        (int32_t*)output_tokens, output_tokens_len, false, true);
+    if (r < 0)
+        return -r;
+    return r;
+}
+
+static LlgTokenizer *llama_sampler_llg_new_tokenizer(const struct llama_model * model) {
+    // TODO store the tokenizer in the model somehow
+    static const struct llama_model *model_cache;
+    static LlgTokenizer *tokenizer_cache;
+
+    if (model_cache == model) {
+        return llg_clone_tokenizer(tokenizer_cache);
+    }
+
+    auto tok_eos = llama_token_eot(model);
+    if (tok_eos == LLAMA_TOKEN_NULL)
+        tok_eos = llama_token_eos(model);
+
+    size_t vocab_size = llama_n_vocab(model);
+
+    auto token_lens = new uint32_t[vocab_size];
+    // we typically have ~7 bytes per token; let's go on the safe side here
+    auto token_bytes_size = vocab_size * 16 + 1024 * 1024;
+    auto token_bytes = new uint8_t[token_bytes_size];
+
+    size_t offset = 0;
+    for (size_t i = 0; i < vocab_size; i++) {
+        size_t max_token = 1024;
+        if (token_bytes_size - offset < max_token) {
+            GGML_ABORT("token_bytes buffer too small\n");
+        }
+
+        llama_token token = i;
+        auto dp = (char *) token_bytes + offset;
+        auto size = llama_detokenize(model, &token, 1, dp, max_token, false, false);
+        if (size < 0) {
+            GGML_ABORT("llama_detokenize failed\n");
+        }
+        if (size == 0) {
+            size = llama_detokenize(model, &token, 1, dp + 1, max_token - 1, false, true);
+            if (size < 0) {
+                GGML_ABORT("llama_detokenize failed\n");
+            }
+            if (size != 0) {
+                *dp = '\xff'; // special token prefix marker
+                size += 1;
+            }
+        }
+
+        token_lens[i] = size;
+        offset += size;
+    }
+
+
+    LlgTokenizerInit tinit = {
+        /* .vocab_size                         = */ (uint32_t)vocab_size,
+        /* .tok_eos                            = */ (uint32_t)tok_eos,
+        /* .token_lens                         = */ token_lens,
+        /* .token_bytes                        = */ token_bytes,
+        /* .tokenizer_json                     = */ nullptr,
+        /* .tokenize_assumes_string            = */ false,
+        /* .tokenize_fn                        = */ llama_sampler_llg_tokenize_fn,
+        /* .use_approximate_greedy_tokenize_fn = */ false,
+        /* .tokenize_user_data                 = */ model,
+    };
+
+    char error_buffer[1024];
+    LlgTokenizer *tokenizer = llg_new_tokenizer(&tinit, error_buffer, sizeof(error_buffer));
+
+    delete[] token_bytes;
+    delete[] token_lens;
+
+    if (tokenizer == nullptr) {
+        LLAMA_LOG_ERROR("llg tokenizer error: %s\n", error_buffer);
+        return tokenizer;
+    }
+
+    if (tokenizer_cache) {
+        llg_free_tokenizer(tokenizer_cache);
+    }
+    model_cache = model;
+    tokenizer_cache = tokenizer;
+
+    return tokenizer;
+}
+
+struct llama_sampler * llama_sampler_init_llg(const struct llama_model * model, 
+        const char * grammar_kind, const char * grammar_data) {
+    auto * ctx = new llama_sampler_llg;
+
+    if (grammar_kind != nullptr && grammar_kind[0] != '\0') {
+        auto tokenizer = llama_sampler_llg_new_tokenizer(model);
+        *ctx = {
+            /* .model        = */ model,
+            /* .grammar_kind = */ grammar_kind,
+            /* .grammar_data = */ grammar_data,
+            /* .tokenizer    = */ tokenizer,
+            /* .grammar      = */ llama_sampler_llg_new(tokenizer, grammar_kind, grammar_data),
+            /* .llg_res      = */ {},
+            /* .has_llg_res  = */ false,
+        };
+    } else {
+        *ctx = {
+            /* .model        = */ model,
+            /* .grammar_kind = */ {},
+            /* .grammar_data = */ {},
+            /* .tokenizer    = */ nullptr,
+            /* .grammar      = */ nullptr,
+            /* .llg_res      = */ {},
+            /* .has_llg_res  = */ false,
+        };
+    }
+
+    return new llama_sampler {
+        /* .iface = */ &llama_sampler_llg_i,
+        /* .ctx   = */ ctx,
+    };
+}
+
+#endif
diff --git a/common/sampling.cpp b/common/sampling.cpp
index 7241ac321..e12301bc4 100644
--- a/common/sampling.cpp
+++ b/common/sampling.cpp
@@ -151,9 +151,26 @@ struct common_sampler * common_sampler_init(const struct llama_model * model, co
 
     lparams.no_perf = params.no_perf;
 
+    struct llama_sampler * grmr;
+    if (params.grammar.compare(0, 4, "llg:") == 0) {
+#ifdef LLAMA_LLGUIDANCE
+        auto gp = params.grammar.find(':', 4);
+        if (gp == std::string::npos) {
+            GGML_ABORT("invalid serialized grammar");
+        }
+        auto grm_type = params.grammar.substr(4, gp - 4);
+        auto grm_data = params.grammar.c_str() + gp + 1;
+        grmr = llama_sampler_init_llg(model, grm_type.c_str(), grm_data);
+#else
+        GGML_ABORT("llguidance (LLAMA_LLGUIDANCE cmake parameter) is not enabled");
+#endif
+    } else {
+        grmr = llama_sampler_init_grammar(vocab, params.grammar.c_str(), "root");
+    }
+
     auto * result = new common_sampler {
         /* .params = */ params,
-        /* .grmr   = */ llama_sampler_init_grammar(vocab, params.grammar.c_str(), "root"),
+        /* .grmr   = */ grmr,
         /* .chain  = */ llama_sampler_chain_init(lparams),
         /* .prev   = */ ring_buffer<llama_token>(std::max(32, params.n_prev)),
         /* .cur    = */ {},